Car sound

One of my earliest childhood memories is of sitting in the front seat of my father’s Studebaker, listening to the Beatles. Since those early days in Lubbock, Texas, I’ve listened to a great deal more music in many more cars. In the Studebaker, and in the ’63 Plymouth that followed it, if you wanted to listen to music, you listened to AM Radio. But then in the early ’70s we got the Toyota–and my brother installed an eight-track in it.

We didn’t know it then, but that was just one shot in a revolution that led to today, when most cars (including my own) have stereo systems far superior to the one in my living room, and some people are so (BOOM!) enamored with them (BOOM!) that they want to share them (BOOM!) with everyone (BOOM!) else (BOOM!) in the city (BOOM!).

A modern car stereo system combines a number of high-tech devices in an effort to get around one inescapable fact: the inside of a car is not a good place listen to a stereo system. Acoustically, it’s a mess: soft areas that absorb sound, glass windows that bounce it around, and people that aren’t centered between the speakers. Throw in tires on the highway, air rushing over the vehicle, and several thousand small gasoline explosions per minute, and it’s a wonder we can hear anything at all.

There are three main components to a car stereo system: a tuner or receiver, amplifiers, and speakers.

Tuners and receivers are similar, except receivers have built-in amplifiers and tuners don’t. Both tune in AM and FM radio waves and usually also contain a cassette player, CD player or mini-disk player.

Amplifiers are necessary because the fluctuating electrical signal that is the output of the receiver is not powerful enough to drive a speaker. Amplifiers turn that barely-noticeable fluctuating current into big, powerful, “Wow, would you listen to that!” current. The more powerful the current the amplifier produces, the potentially louder the sound is. Car stereo amplifiers can deliver anywhere from 50 to 500 watts of output. Five hundred watts ensures that people in neighboring provinces can enjoy your music just as much as you do. For us ordinary mortals, a mere 100 watts is generally enough.

The amplified current goes on to drive speakers. Speakers contain a coil inside or surrounding a magnetic field, produced by (what else?) a magnet. The varying amplified current sets up a varying magnetic field in the coil, which is alternately attracted and repelled by the field of the speaker magnet. This causes the coil to vibrate; its vibrations vibrate in turn a large diaphragm, which sets up matching vibrations in the air: in other words, sound.

Car speakers come as “woofers” and “tweeters.” A woofer is a cone-shaped, large speaker that is particularly good at reproducing low frequencies. Tweeters are small cone- or dome-shaped speakers that are particularly good at reproducing high frequencies. You can also get sub-woofers, very large speakers that reproduce the very lowest sounds.

Most car speakers are “coaxial” or combination speakers, which have a small dome-shaped tweeter in the center of a large woofer. Better sound can be achieved by mounting separate tweeters high on the doors or on the windshield pillars, where they can deliver their higher frequencies without being blocked by the seats and dash. Woofers are usually located in the rear, and sub-woofers require their own separate enclosure. The large trunks of sedans give them an edge in this department, acting as resonating chambers that enhance the bass.

Of course, mere speakers and tuners and amplifiers aren’t enough for the true connoisseur. They’ll shell out even more for electronic “crossovers,” which separate the components of a sound into high and low frequencies and direct them toward the appropriate speaker drivers before they’re even amplified. Or maybe they’ll go all the way and look for “DSP,” which stands for digital signal processing. This computerized system makes carefully massages audio signals to recreate the sound of a concert hall, cathedral, night club or other specific venue.

It’s probably just a matter of time before car stereos become so good that they’ll make the music sound even better than when it was live…which conjures up an interesting picture of an empty concert hall whose parking lot is full of people sitting in their cars, listening to the concert being broadcast via digital radio signals to their state-of-the-art stereo systems.

Drive-in concerts. It’s an idea whose time has come–and you read it here first.

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